Scientific Forecaster Discussion
fxus66 kpdt 210522
Area forecast discussion
National Weather Service Pendleton or
1022 PM PDT sun Oct 20 2019
Updated aviation discussion
Short term...tonight and Monday...a northwest flow will continue
over the region. A weak system passing through this flow is
generating some light precipitation over far eastern Washington and
northeast Oregon. Precipitation will decrease overnight to just a
few showers mainly over the northeast Oregon mountains and linger
into Monday. Another passing system is expected to increase
precipitation across eastern Washington and northeast Oregon late in
the afternoon and evening period.
Aviation...06z tafs...VFR conditions overnight with some
locally breezy conditions. Cigs will lower to bkn-ovc 5-8kft Monday
afternoon and evening as some rain develops mainly impacting kpdt
and kalw. Winds will generally be 7-15kts through the period but
some brief stronger winds possible.
Previous discussion... /issued 236 PM PDT sun Oct 20 2019/
Short term...tonight through Wednesday. A weather system will
pass through the eastern sections of the area this evening.
Showers will persist overnight in the mountains with the best
chances of pcpn over The Blues and wallowas. Snow levels should
start out above 5k feet but slowly lower to 4k and minor snow
accumulations are possible above this level.
Meanwhile drier air will filter into the region from the west
overnight followed by a weak disturbance that is forecast to track
through the area tomorrow morning. Clouds and showers will be on
the increase and a stronger disturbance is expected to further
increase and expand the area of pcpn Monday afternoon. This system
also tracks away from the area tomorrow night with drier
conditions expected. Another disturbance will approach the two
state area from the north on Tuesday and temperatures will be
noticeably warmer. Showers will develop over south central
Washington Tuesday morning and push into Oregon by the afternoon
and evening. A weak ridge of high pressure builds into the area late
Tuesday night and Wednesday and cooler temperatures are expected.
Long term...Wednesday night through Sunday...models in fairly good
agreement, especially early on. Northwesterly flow aloft will become
more zonal as ridging builds onshore through Thursday. Ridge
flattens and shifts south on Friday as a quick moving cold front
swings through the northwest, bringing mountain showers and breezy
winds. The overall pattern for the weekend becomes highly amplified
with strong upper level ridging building off the West Coast into
western British Columbia. Cold and dry Canadian air filters into the region for
the weekend as a stronger cold front and upper-level trough drop
south along the east side of the ridge and dig over the western US.
A few mountain showers will still be possible for the weekend,
especially on Saturday. Seasonably mild temps through Friday with
highs in the mid 50s to mid 60s, cooling behind the frontal passages
through the weekend, with highs in the 40s to mid 50s.
Preliminary point temps/pops...
PDT 44 60 49 66 / 10 20 30 30
alw 45 59 51 66 / 20 30 40 40
psc 46 61 53 70 / 10 20 20 10
ykm 36 57 43 68 / 10 30 30 20
hri 47 62 52 69 / 10 10 20 20
eln 38 53 45 63 / 10 50 50 20
rdm 34 63 39 64 / 10 0 10 20
lgd 38 52 45 59 / 60 30 40 40
gcd 38 55 41 61 / 20 10 10 20
dls 46 60 51 66 / 10 20 30 50